LCLUC 2016 Webinar Series

The 2016 LCLUC Webinar Series features LCLUC projects focusing on detection and monitoring of land-cover and land-use changes. These projects contribute to the revised science questions identified in the land use land cover change theme of the 2003 U.S. Climate Change Science Program Strategic Plan.

Improved time-series of medium spatial resolution data are enabling advances in crop type mapping and monitoring. In this presentation, we describe methods for generic crop type cultivated area assessment at national-scales, highlighting challenges related to the complexity and diversity of crop phenologies, variable field sizes, and management techniques. Results indicate the feasibility of operational monitoring of key commodity crops at the global scale.

The agricultural frontier in Brazil is focused in the lands to the south and east of the Legal Amazon in the Cerrado biome, a biodiversity hotspot. The rates of land conversion from natural land cover to mechanized land cover was very rapid at the beginning of the century but has since slowed. Accompanying this slowing has been an enormous rise the use of double cropping. We are analyzing the rates of conversion and the transformation to extensive double cropping with satellite data and understanding theses changes and their consequences in the context of socioeconomic analyses.

We have known that tropical deforestation changes the surface energy balance and water cycle. We have recently come to understand that it is the largest source of climate change in the Amazon and that the amount of change that occurs strongly depends on how the land is used following deforestation. Using a combination of field research, satellite remote sensing, and computer modeling, we show how agricultural expansion has altered climate in southeastern Amazonia, why management practices matter, and how protected forests mitigate the impacts.

The spatial distribution of agricultural fields is a fundamental description of rural landscapes. The size of fields is indicative of the degree of agricultural capital investment, mechanization and labor intensity. Field size distributions and their changes have not been studied over large areas as field size datasets are not publicly available. Changing field sizes may have significant impacts on landscape spatial configuration and land use diversity with ecological and biogeochemical consequences. Satellite data and, in particular, the data provided by the near-global long term Landsat series, provide the potential to monitor field size changes and provide geographic context for observed changes. Results showing field size changes around the world are first presented. Then the results of a computer vision approach to extract field sizes automatically from Landsat 5 TM and Landsat 7 ETM+ 30m time series are presented. Notably, in 2010 for all the conterminous United States (CONUS) a total of 4.18 million fields were extracted with mean and median field sizes of 0.193 km2 and 0.278 km2 respectively. The results were validated by comparison with field boundaries manually digitized from Landsat 5 and Google-Earth high resolution imagery. Recommendations for future work including global application are discussed.

Increasing small-scale agricultural production is a primary goal of many development organizations. However, studies that investigate the ways that small scale agricultural production impacts health outcomes related to food insecurity are rare. One of the challenges in conducting these types of investigations is the lack of necessary data at a relevant spatial and temporal scale. In this project we use a remotely sensed based estimate of food production that are useful at the micro scale in West Africa. We combine this remotely sensed data with health survey data, the Demographic Health Survey (DHS), to evaluate food insecurity outcomes of young children. Our results suggest that while food production is important, individual and community responses to food management are potentially more significant.

For over four decades, food production sub-Saharan Africa has been dominated by smallholders with low yields (1 ton/ha) for most staple food crops. Soils have been depleted from continual net removals of carbon and nitrogen and limit yield potentials. To address widespread food insecurity, Malawi tackled these problems through a national scale subsidy program (FISP) that provides fertilizers and improved seeds to smallholder farmers, key tenants of the 21st C African Green Revolution. National yields have been double or triple the historical average since the start of FISP in 2005/6 harvest. Here, we present shifts in agricultural area and productivity using a suite of remote sensing data sets, demonstrating the application of coarse data products to smallholder agriculture as well as the complex interplay of climate and FISP. We also find the FISP has important impacts on food security and noteworthy outcomes for childhood stunting.

Climate change is expected to alter the timing and quantity of water available for irrigated agriculture across the western United States. The economic effects of these changes have proven difficult to quantify because water rights complicate the relationship between climate signals and the amount of water available to an individual farmer. To understand how farmers will respond to climate change, it is necessary to describe how water rights interact with climate to drive decision making at the scale of the individual farmer. We combine land-use observations derived from Landsat with geospatial data on water rights and socioeconomic variables to investigate how water rights affect land-use decision making in the Eastern Snake River Plain of Idaho. We demonstrate that water rights generate an economically inefficient pattern of land use when farmers with relatively insecure water rights plant a less profitable set of crops to hedge against the probability of a water shortage. This inefficiency generates a loss in annual profit of up to 6.3% for those irrigators with the least secure water rights. However, ownership of a portfolio of water rights can mitigate this profit loss. The most advantageous water right portfolio combines access to an irrigation district with private water rights, reducing annual profit losses to 1.4%. As climate change places increasing stress on water availability across the western United States, these empirical results illustrate that water rights will skew the level and distribution of economic welfare in the region by influencing land-use decisions.

The highest non-glacierized elevations of Bolivian and Peruvian Andes harbor unique alpine wetlands (termed bofedales), often just below or in close proximity to the region’s mountain glaciers and their meltwater streams. Composed of a dense carpet of cushion plants, these systems are both biologically unique and economically important; they provide critical year-round islands of nutritious forage for an extensive highland system of pastoral agriculture (llama and alpaca production). However, in many areas they appear to be in a state of decline, and as they are often fed directly by glacier meltwater streams, we hypothesized that rapid glacier recession had the potential to negatively impact these systems, and the local livelihoods dependent on them. In this project, we sought a better understanding of the processes occurring by analyzing landcover change; running and evaluating the outputs of regional climate models to understand how climate change will likely impact the region; and by studying the hydrology and biology of a few sites in detail to better understand the physical processes occurring. Such knowledge may provide useful information for local adaption strategies, and to mitigate the negative impacts of development activities, such as mining and construction of new dams.

Current estimates of carbon-equivalent emissions report the contribution of deforestation as 12% of total anthropogenic carbon emissions (van der Werf et al., 2009), but accurate monitoring of forest carbon balance should discriminate between land use change related to forest natural disturbances, and forest management. The total change in forest cover (Gross Forest Cover Loss, GFLC) needs to be characterized based on the cause (natural/human) and on the outcome of the change (regeneration to forest/transition to non/forest)(Kurtz et al, 2010). We propose a methodology for post-processing forest cover loss maps (Hansen et al., 2013) by classifying each forest cover loss detection as either (a) deforestation, (b) fire and insect disturbances or (c) forest management practices. The classification methodology is based on the object-oriented analysis of temporal spectral profiles of the areas of forest cover loss. The methods are demonstrated by wall-to-wall classification of the forest cover loss in the conterminous United States for the 2002-2011 period.

Timber harvest history has broad implications for forest management, timber market, ecosystem carbon, and environmental change, but historical timber harvest data, if exist, lack needed spatial and temporal details. The long term Landsat record together with available inventory data makes it possible to reconstruct timber harvest history over multiple decades. In this webinar, we present a suite of methods developed for mapping timber harvest area, intensity, and timber volume using these datasets, and evaluate the spatial and temporal patterns of a 25-year timber harvest history reconstructed using these methods for the state of North Carolina.

Tropical forest conversion is a major driver of climate change, and contributes as much as 25% of global carbon dioxide emissions. The main agent of deforestation and degradation over the last twenty years has been the conversion of closed canopy tropical forests to agriculture. Logging and forest management have not been as important as outright clearing of forests for agriculture, even while some early reports have painted a dire picture of a looming threat from commercial logging in the Amazon and some other areas. These threats have not turned out to as quantitatively significant as once feared and seem isolated to key hot spots but not widespread. Further, the reported strong link between logging, understory fire, and forest conversion does not appear to hold true except in some key local hot spots. However, it is the premise of this project that the issue is far from being resolved. First, the vast majority of research has been focused on selective logging and degradation in intact natural forests, usually considered as a form of one-off harvest or culling rather than a form of intensive forest management. This is a very different phenomenon than the establishment of industrial forests (IF) in natural forestland as well as on non-forest land, which are associated with the dynamics of management and rotation. Second, the studies done to-date are geographically limited and thus may represent special cases not reflective of a general or widespread LCLUC phenomenon. As such we need to have a much better understanding of the extent and dynamics of industrial forestry and commercial forest logging – empirically and from the perspective of understanding drivers.

Preliminary evidence suggests that here are large and increasing investments being made in land resource development by all types of investors, from smallholders to industry. More precisely, these megatrends are forcing large scale shifts in land use and land cover; for instance natural forests and food-based agriculture systems are being converted to industrial tree systems (plantations). Early observations suggest that the area of industrial forest land use is increasing globally. More interesting, there appears to be significant geographic shifts in the location of new industrial tree systems, as industrial wood production that has historically been located in the temperate zone is now moving to tropical production centers and source regions.

The areas of industrial forest plantations have expanded substantially in recent years across tropical regions, in particular tropical monsoon Asia. However, the information on the area, spatial distribution and temporal dynamics of industrial forest plantations in tropical monsoon Asia are incomplete and outdated. In this presentation, we present the results from our NASA project that combines optical (Landsat, MODIS) and synthetic aperture radar (PALSAR, Sentinel-1) images to identify and map industrial forest plantation in tropical monsoon Asia. The algorithms will facilitate timely and accurate mapping of industrial forest plantations in the region and the results will expand community knowledge about industrial forest plantations.

Summary: Dr. Garik Gutman is Program Manager for the NASA Land-Cover/Land-Use Change (LCLUC) Program. His current research interests include the use of remote sensing for detecting changes in land cover and land use, and analyzing the impacts of these changes on climate, environment and society. His NASA research program helps to develop the underpinning science and promotes scientific international cooperation through supporting the development of regional science networks over the globe under the GOFC-GOLD international program.